The Drug Evaluation Branch of the Developmental Therapeutics Program, Division of Cancer Treatment (DCT), National Cancer Institute (NCI) is seeking a contractor with the expertise to evaluate compounds for anticancer activity in experimental tumor models, including both murine tumors growing in conventional mice and human tumors growing in athymic mice. Emphasis will be placed on testing congeners and pro-drugs of newly identified lead compounds (synthetic and natural product) under well-controlled experimental conditions in order to guide synthetic efforts and identify the most promising member of a class for further development. Also a limited number of secondary evaluations will be performed to address specific questions related to anticancer activity which arise during the course of developing agents to clinical trial.